Bore evacuator for artillery type guns



Feb. 25, 1964 Filed June 6, 1962 D. M. ROECK, SR 3,122,055

BORE EVACUATOR FOR ARTILLERY TYPE GUNS 2 Sheets-Sheet 1 INVENTOR. Dun-11d IVLRnEck 51:

$25M; 9 mi 2%? Feb. 25, 1964 I D. M. ROECK, SR 3,122,055

BORE EVACUATOR FOR ARTILLERY TYPE GUNS Filed June 6, 1962 2 Sheets-Shee 2 EELLH;

INVENTOR.

g 4.7901201; 9 0-d wM United States Patent BORE EVACUATOR FOR ARTILLERY TYPE GUNS Donald M. Roeck, Sn, Troy, N.Y., assignor to the United States of America as represented by the Secretary of the Army Filed June 6, 1962, Ser. No. 200,590 1 Claim. (Cl. 891) (Granted under Title 35, U.S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to artillery type guns and more particularly to the bore evacuators therefor.

With those cannons and howitzers in which the breech opens into a confined compartment, as in a tank, it is important that the noxious discharge fumes be evacuated from the muzzle end of the firing tube bore as the breech is opened to prevent the fumes from entering the compartment and harmfully affecting the gunners therein.

This evacuation is generally automatically effected by an evacuator mounted on the firing tube. In order to properly evacuate the noxious fumes it is necessary to charge the evacuator from the compressed gases produced in the firing tube bore rearwardly of an energized shell and then after the shell leaves the bore discharge the trapped gas back into the bore in a manner to induce a forward flow of the air therein.

The design of -a rugged and reliable check valve evacuator system for low pressure howitzers and tank cannons has long been a problem in the specialized field of cannon design as previously the check valves have been actuated by gas pressure. -It is the object of this invention to provide for artillery type guns a bore evacuator having a check valve which is actuated by inertia forces produced by gun recoil with the evacuator being simple but rugged in construction and positive in operation.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a reduced elevation view of a howitzer with the evacuator mounted on the firing tube;

FIG. 2 is a view taken along line 22 of FIG. 1;

FIG. 3 is a view taken along line 33 of FIG. 2 and shows the bafile ring in the open position and the rear end of the discharged shell positioned past the intake port but blocking the exhaust port;

FIG. 4 is a view similar to FIG. 3 but showing the bafile positioned so as to close the intake ports and the exhaust ports open to exhaust the trapped gases in the evacuator chamber to the bore of the firing tube after the shell has left the muzzle end thereof.

Shown in the figures is a howitzer 12 having a firing tube 14 with a bore 16, a breech closure member 18 actuatable between a breech open and a breech closed position, and an evacuator 20 fixedly mounted on the firing tube. Firing tube 14 is displaceable by recoil forces produced by the discharge of a round therein.

Evacuator 20 includes a cylindrical shell 22 having a rear end 24 and a front end 26 respectively provided with a hole Which matingly receives firing tube 14 and such front and rear ends are sealed gas tight relative to the outside surface of the firing tube to form a pressure chamber 28 in the shell. The surface of firing tube 14 extending forwardly of rear end 24 of shell 22 is machined to form a smooth surfaced mounting section 30 on which there is slidingly mounted a baflle ring 32 to be hereinafter described. The front wall of rear end 24, noted at 34, extends from mounting section 30 at right angles relative thereto.

Three intake ports 36 extend radially between bore 16 and chamber 28 to provide communication therebetween and they are located so that the ends thereof within shell 22 are located in mounting section 30 immediately forward of front wall 34. The intake ports 36 are symmetrically disposed apart. Extending between bore 16 and chamber 28 forwardly of mounting section 30 are three symmetrically disposed exhaust ports 38 which are smaller in diameter than intake ports 36 and which are arranged to incline downwardly and forwardly from the chamber 28 at about a 30 angle relative to the central axis of the bore.

Baffle ring 32 includes a collar portion 40 which has sliding contact with mounting section 30 and a plurality of lobes 44 which extend outwardly from the rear edge of the collar and at right angles thereto, so that the rear faces of the lobes are contactable with front Wall 34. Provided longitudinally through each of the lobes 44 is an orifice 46 which slidingly receives a threaded stud 48 wtih a head 50 of larger diameter. Each of the studs 48 is threadingly received by an aperture 51 in rear end 24 so as to extend forwardly therefrom. The studs 48 are tightened into rear end 24 so that heads 50 are similarly spaced from front wall 34 and are all spaced therefrom so as to permit relative longitudinal displacement of baffle ring 32 and firing tube 14 between a first relative position wherein intake ports 36 are covered by collar portion 40 and the rear faces of lobes 44 are in contact with the front wall 34 and a second relative position wherein the collar portion is displaced forwardly of the intake ports on mounting section 30. A compressible coil spring 52 is mounted on each of the studs 48 between the rear face of head 50 and the front face of the lobes 44 so as to act mutually in biasing baffle ring 32 to the first relative posi tion. The tension applied by springs 52 to bafile ring 32 is arranged to be overcome by the inertia produced therein by recoil forces when a round is discharged in firing tube 14.

Thus, before a round is fired in firing tube 14, battle ring 32 is spring biased to the first relative position with the intake ports 36 closed thereby. When a round is fired in firing tube 14, howitzer 12 recoils but through inertia forces restraining displacement of baffle ring 32, firing tube 14 moves relative to the baffle ring against the bias of the springs 52, to locate the bafile ring in the second relative position by the time the discharged shell, noted at 54, passes intake ports 36. With the outer ends of the intake ports 36 uncovered, the compressed discharge gases rearwardly of shell 54 are discharged through the intake ports into chamber 28 and more of the gases are discharged through the exhaust ports 38 when the shell moves thereby.

When the accelerative recoil forces in firing tube 14 drop in value to Where the inertia forces in bafile ring 32 are overcome by the bias of the springs 52, the baflie ring is displaced thereby to the first relative position, blocking intake ports 36. Upon exit of shell 54 from the muzzle of firing tube 14, the pressure of the gases in bore 16 drops and when the pressure in the bore is below that in chamber 28 the gases therein are discharged therefrom through exhaust ports 38 into the bore.

Because of the inclination of the exhaust ports 38, the gases discharged therefrom cause the residual gases forwardly thereof in bore 16 to be driven forwardly therefrom. This results in a low pressure area in bore 16 in back Of exhaust ports 38, causing the remaining gases in the bore to flow forwardly out the muzzle end thereof when breech closure member 18 is actuated to the open position. The diameter of the exhaust ports are designed to prolong the discharge of the gases from chamber 28 long enough to provide ample time for the actuation of breech closure member 18 to the breech open position.

From the foregoing it is clearly apparent that there is provided herein for artillery type guns a bore evacuator which is simple and rugged in construction and which is operable even though low pressure ammunition is used in the guns, with the valve acting baifie ring being actuatable by recoil forces rather than by discharge gas pressure.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claim is intended to include such variations.

1 claim:

A gun including a firing tube displaceable responsive to recoil forces, a bore in said firing tube, a breech closure member actuatable between a breech open and a breech closed position, a bore evacuator fixed mounted on said firing tube so as to form a pressure chamber, said evacuator having a rear end with a front wall, a smoothly machined cylindrical mounting portion formed on said firing tube so as to extend forwardly from said front wall, a plurality of intake ports extending through said firing tube at said mounting portion to provide communication between said bore and said chamber, a plurality of exhaust ports extending through said firing tube forwardly of said exhaust ports to provide communication between said bore and said chamber, a'bafile ring including a collar portion mounted on said mounting portion for relative sliding displacement respective to said firing tube and a plurality of lobes extending outwardly at right angles from the rear edge of said collar portion, said intake portionsbeing positioned so as to be blocked by said collar portion when said lobes are in contact with said front wall, an orifice extending longitudinally through each of said lobes, a stud slidingly received by each of said orifices and threadingly received by a corresponding aperture in said rear wall, a head formed on each of said studs, and springs respectively mounted 'on said studs between said head thereon and the associated ones of said lobes for biasing said bafiie ring from a position on said mounting portion wherein said intake ports are unblocked into contact with said front wall, the combined tension of said springs being arranged so as to be overcome by the inertia of said bafile plate so that said firing tube is'displaoeable by recoil forces relative to said baflie ring to unblock said intake ports.

References Sites! in the file of this patent UNITED STATES PAT ENTS 2,427,374 Walker Sept. 16, 1947 2,807,986 Howard et al. Oct. 1, 1957 3,024,706 Wild Mar. 13, 1962 3,058,400 Hailston et al Oct. 16, 1962 

